You will need the IP of the server you want to join.
There are several out there not counting the VA's which can have there own network. Alot of VA's use VATSIM some use IVAO. In order to get the best realism you need a voice program as well TEAMSPEAK OR SQUAKBOX are just a few that are being used. You might want to consider a VA as most of them are very beginer friendly. I belong to one that is very beginer oriented. It is not mandatory that you fly on line nor do you have to stick at one hub but can choose to fly from any hub you desire. I am not trying to persuade you to join my VA but if you want to check it out the link is
www.flightbase2000.comIn order to join you will need to fly a flight first but it is your choice as to which flight you want to fly. You will be paid with virtual money for the flight. If you like what you see you can even become a employee of the VA like myself. I am a HUB MANAGER for KGSO Grensourgh North Carolina.